XML 31 R19.htm IDEA: XBRL DOCUMENT v2.4.0.6
Investments (Details) (USD $)
In Thousands, unless otherwise specified
Aug. 31, 2012
May 31, 2012
Summary of investments    
Gross Amortized Costs $ 15,998 $ 16,998
U. S. Treasury Bills [Member]
   
Summary of investments    
Gross Amortized Costs 15,998 16,998
Gross Unrealized (Losses) Gains 3 5
Fair Value $ 16,001 $ 17,003